Nitric Oxide
Nitric Oxide - Nitric oxide (NO) has recently generated an explosion of interest as it acts as a novel type of neurotransmitter; unlike conventional neurotransmitters, which are released from one neuron to another in a predefined synaptic pathway, NO is produced on demand and theoretically can diffuse between neurons to affect signaling in the surrounding area. These properties suggest that NO plays a role in widespread signaling, and has specifically been implicated in the light/dark adaptation process in the vertebrate retina. Though NO synthase (NOS), the producer of NO, is present in all major retinal cell types, the actual production and behavior of NO in vivo has yet to be fully characterized. By loading retinas with the fluorescent NO-binding dye diaminofluorescein (DAF), NO induced fluorescence (NO-IF) can be imaged in real time. This study used real-time imaging techniques in turtle (Pseudemys scripta elegans) retinal slices to characterize the production and behavior of NO. Though specific stimulation patterns could not be replicated or isolated due to methodological constraints, it was found that NO-IF is produced in two discrete kinetic profiles that are not correlated with cell types, and that, contrary to theory, extracellular NO-IF diffusion is highly restrained, or nonexistent.